Mass extinction due to high ocean acidity: Study

September 17, 2011, 10:18 am
Source: The Vancouver Sun
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Canadian-led team solves biggest mystery in Earth history

This map shows the orientation of the Earth's land masses in the supercontinent Pangea, about 250 million years ago, at the time of the greatest mass extinction in the planet's history.Photograph by: handout photo, Ron Blakey, Northern Arizona University

A Canadian-led team of scientists may have solved the biggest whodunit in Earth history in a study showing that the all-time greatest mass extinction on the planet - which wiped out about 90% of all species 250 million years ago - appears to have been linked to rising levels of ocean acidity.

Researchers have long believed that massive volcanic eruptions in present-day Siberia - or possibly a huge meteorite strike - triggered the so-called PermianTriassic extinction. But the precise mechanism of death for so many species remains a subject of debate, with some scientists convinced it was a resulting lack of oxygen in the Earth's oceans or a greenhouse-gas nightmare that nearly ended all plant and animal life.

But the Canadian study, headed by St. Francis Xavier University climate scientist Alvaro Montenegro, points to ocean acidification as a possible "main culprit" in the harrowing, prehistoric die-off.

And the Nova Scotia researcher told Postmedia News that the finding should serve as a warning about present-day increases in ocean acidification. Though still far lower than that experienced in the ancient mass extinction, rising acidity has been documented by researchers around the world and is linked to the effects of climate change.

Using a series of computer simulations to recreate conditions on the planet at the time, Montenegro and his five colleagues from Canada and Australia found it unlikely that oxygen-starved oceans led to the mass extinction.

Instead, their models pointed to a new prime suspect: spiking acid levels in the world's marine environments.

Runaway ocean acidification "would definitely have a very serious biological impact on ocean calcifiers," said Montenegro, referring to creatures that manufacture their own bodily structures from minerals found in ocean water.

Among the species that vanished from the rock record around the time of the P-T extinction were most of the ammonites - large, snail-shaped marine creatures that are known today from the beautifully iridescent, multi-coloured fossils of their spiral shells, found in places such as southern Alberta. The relatively few ammonite species that survived the mass extinction 250 million years ago were later killed off by the meteorite-linked extinction at the end of the dinosaur age 65 million years ago.

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Lars Tuff wrote: 11-05-2011 22:40:04

The ammonites did NOT die out during the permian extinction. They died out more than 100 million years later, when the dinosaurs did (65 mya). Some other facts: Ocean acidification rise the last 300 years: from pH 8.3 to pH 8.18. Not much. CO2 concentration rise in the air the last 200 years: from 0.029 % to 0.038 %, or less than 1/100 of a percent. Insignificant. Man's contrubition to CO2 rise: Max 3-5 %. Man's total effect on CO2 rise: 0.00045 percent, or about 1/2000 of a percent, over 200 years. Our share of oceanic acidification, 3-5%, giving rise to about 1/200 of a pH unit over 300 years. Both these man-made effects are too tiny to distinguish from the earths natural variations in the CO2 cycle. Nature drives the CO2 cycle, not man. Stopping man's carbon emissions will have no effect or an electron-microscopic effect on the level of CO2 in the air, and thus little effect on acidification of the oceans. Temperature: Stasis in the lower troposphere (where greenhouse warming occurs) for at least 30 years. On earth's surface: Stasis for the last 10 years, declining line the last 12-13 years. CO2 up by approx. 25% and 5 % in those same periods. CO2 is a greenhouse gas, but it's effect diminishes with increasing concentration. The relationship is purely logaritmic. Doubling the CO2 concentration from 0.029 % to 0.058 % will give rise to a temperature increase in the order 1-1.5 deg. celsius, from CO2 alone. Our share of CO2 total emissions the last 100 years, less than 3-5%, probably much smaller (as our emissions have soured over time). Man's contribution to global temperature rise since 1910 (100 years): Less than 0.03 deg. celsius. Fiddling around in Mathematica and making the prediction curves fit empirical data does not represent reality, nor does it change the facts. A prediction graph can be made to fit any given empirical data, past, present and future, and still come out with the desired temperature rise of 1.5, 5, 12 or even 20 deg. celsius. This method was discovered by the english mathematician Taylor and his Scottish collegue MacLaurin between 1715 and 1746. Nothing new about this. It is a part of the curriculum at any introductory cource in mathematics at western universities, and has been so for at least 50 years. Such fidddeling might impress non-scolars and non-science scolars, but is scientifically not interesting to people with scientific training. In the same way. fiddeling with computer models in a modern science lab does not comprise a theory, not even a hypothesis. It's fun to play with models such as these, but they do not tell the truth. Computer modellling can give us ideas about how nature works, butt they are NOT nature. Nor can they answer questions a peer-review demands. The latter is the scientific approach, the first is PlayStation 4 stuff. Please don't keep calling this mass-extinction idea a theory, when it is not as yet a hypothesis.